public class HashBucket {
    static class Node{
        public int key;
        public int val;
        public Node next;

        public Node(int key,int val){
            this.key=key;
            this.val=val;
        }
    }

    public Node[] array;
    public int usedSize;

    public static final double LOAD_FACTOR=0.75;

    public HashBucket(){
        array=new Node[10];
    }

    public void put(int key,int val){
        int index=key%array.length;
        Node cur=array[index];
        while(cur!=null){
            if(cur.key==key){
                cur.val=val;
                return;
            }
            cur=cur.next;
        }
        //头插法
        Node node=new Node(key,val);
        node.next=array[index];
        array[index]=node;
        usedSize++;
        if(calculateLoadFactor()>=LOAD_FACTOR){
            //扩容
            resize();
        }
    }

    private void resize(){
        Node[] newArray=new Node[2* array.length];
        for (int i = 0; i < array.length; i++) {
            Node cur=array[i];
            while (cur!=null){
                Node curNext=cur.next;
                int index=cur.key%newArray.length;
                cur.next=newArray[index];
                newArray[index]=cur;
                cur=curNext;
            }
        }
        array=newArray;
    }

    //计算负载因子
    private double calculateLoadFactor(){
        return usedSize*1.0/ array.length;
    }

    public int get(int key){
        int index=key% array.length;
        Node cur=array[index];
        while (cur!=null){
            if(cur.key==key){
                return cur.val;
            }
            cur=cur.next;
        }
        return -1;
    }
}
